OSMOTIC DRUG DELIVERY SYSTEMS

1. OSMOTIC CONTROLLED
ORAL DELIVERY SYSTEM
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Contents
Introduction
Advantages
Disadvantages
Mechanism:
Osmotic pressure controlled system
Components of osmotic pump
Osmotic pumps:
Elementary osmotic pump
Push Pull osmotic pump
Osmotic brusting osmotic pump
Liquid oral osmotic system
Telescopic capsule for delayed release

3. OROS-CT
Sandwiched osmotic tablets
Monolithic osmotic system
References
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Concept
 Controlled drug delivery is one which delivers
the drug at a predetermined rate, for locally or
systemically, for a specified period of time.
 Continuous oral delivery of drugs at predictable
& reproducible kinetics for predetermined
period throughout the course of GIT.

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Advantages
 Deliveries may be delayed or pulsed if
desired.
 Drug release is independent of gastric pH
and hydrodynamic condition.
 The release mechanisms are not dependent
on drug.
 They are well characterized and understood.

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Disadvantages
 Costly.
 If the coating process is not well controlled there
is a risk of film defects, which results in dose
dumping.
 Size hole is critical.

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Osmotic Pressure Controlled
System
 Provides zero order release
 Drug may be osmotically active, or combined with an
osmotically active salt (e.g., NaCl).
 Semipermeable membrane usually made from
cellulose acetate.
 More suitable for hydrophilic drug.
 Examples: Glucotrol XL, Procardia XL

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Osmosis
- Movement of solvent from lower to higher concentration.
- The passage of solvent into a solution through
semipermeable membrane.
Semipermeable Membrane
Molecules are permitted only to one component
(Water).
Osmotic pressure
It is the hydrostatic pressure produced by a solution
in a space divided by a semipermeable membrane
due to difference in concentration of solutes.

9. Components of osmotic pumps
 Drugs
 Short biological half-life {2-6h}
 Highly potent drug
 Required for prolonged treatment
e.g. nifedipine, glipizide, virapamil
 Osmotic agents
 Osmogents used for fabrication of osmotic
dispensing device are inorganic or organic in
nature
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10.  Inorganic
 Magnesium sulphate
 Sodium chloride
 Sodium sulphate
 Potassium chloride
 Sodium bicarbonate
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11.  Organic
 Sodium carboxymethyl cellulose
 Hydroxypropylmethyl cellulose
 Hydroxyethylmethylcellulose
 Methylcellulose
 Polyethylene oxide
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12.  Semi Permeable Membrane
The Semi Permeable Membrane must meet some
performance criteria :
 The material must posses sufficient wet strength
so as to retain its dimensional integrity.
 The membrane exhibit sufficient water
permeability so as to retain water flux rate in the
desired range.
 The membrane should also be biocompatible

13. Elementary osmotic pump
 Coating of an osmotically
active agent with the rate
controlling semipermeable
membrane.
 This membrane contains
an orifice of critical size
through which agent is
delivered.
 The dosage form after
coming into contact with
aqueous fluids, imbibes
water 13

14.  This osmotic imbibitions of water result in formation of a
saturated solution of drug within the core.
 60 -80 percent of drug is released at a constant rate but a
lag time of 30-60 minute is observed in most of the cases
as the system hydrates before zero order delivery from the
system begins.
 These system are suitable for delivery of drugs having
moderate water solubility.
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15. Push Pull osmotic pump
 it is possible to deliver
both poorly water-soluble
and highly water soluble
drugs at a constant rate.
 One layer contains drug in
formulation of polymeric,
osmotic agent and other
tablet excipients.
 The tablet core is coated
with semipermeable
membrane.
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16.  After the coating has been applied, a small hole is drilled
through the membrane on the drug layer side of the tablet.
 When the system is placed in aqueous environment water
is attracted into the tablet by an osmotic agent in both the
layers.
 the expansion of non drug layer pushes the drug
suspension out of the delivery orifice.
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17. Osmotic brusting osmotic pump
 delivery orifice is absent and size may be smaller.
 When it is placed in an aqueous environment, water is
imbibed and hydraulic pressure is built up inside until the
wall rupture and the content are released to the
environment.
 Varying the thickness as well as the area the
semipermeable membrane can control release of drug.
 useful to provide pulsated release.
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18. Liquid Oral osmotic system
 deliver drugs as liquid formulations and combine the
benefits of extended release with high bioavailability.
 includes a liquid drug layer, an osmotic engine or push
layer and a semipermeable membrane coating.
 In the aqueous environment water permeates across the
rate controlling membrane and activate the osmotic layer.
 The expansion of the osmotic layer result in the
development of hydrostatic pressure inside the system,
there by forcing the liquid formulation to be delivered from
the delivery orifice.
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19. Telescopic Capsule For Delayed
Release
 consists of two chambers, the first contains the drug and an
exit port, and the second contains an osmotic engine. a
layer of wax like material separates the two section.
 The bilayer tablet with the osmotic engine is placed into a
completed cap part of the capsule.
 The open end of the filled vessel is fitted inside the open
end of the cap, and the two pieces are compressed together
until the cap, osmotic bilayer tablet and vessel fit together
tightly.
 As fluid is imbibed, the osmotic engine expand and exerts
pressure on the slidable connected first and second wall
sections. 19

20.  Negligible pressure gradient develops when the volume of
the reservoir containing the active agent is kept constant.
 the net flow of environmental fluid driven by the pressure
entering the reservoir is minimal and consequently no
agent is delivered for the period.
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21. OROS-CT
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22.  for targeting delivery of drugs to the colon.
 it can comprise of as many as five to six push pull osmotic
unit filled in a hard gelatin capsule or a single osmotic
agent .
 After coming in contact with the gastric fluids, gelatin
capsule dissolves.
 the enteric coating dissolves and water is imbibed into the
core thereby causing the push compartment to swell.
 flowable gel is formed in the drug compartment, which is
pushed out of the orifice at a rate, which is precisely
controlled.
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23. Sandwiched Osmotic Tablets
(SOTS)
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24.  composed of polymeric push layer sandwiched between
two drug layers with two delivery orifices.
 When placed in the aqueous environment the middle push
layer containing the swelling agents swells and the drug is
released from the two orifices situated on opposite sides of
the tablet.
 suitable for drugs prone to cause local irritation of the
gastric mucosa.
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25. Monolithic osmotic system
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26.  simple dispersion of water-soluble agent in polymer
matrix.
 Water imbibtion by the active agents takes place
rupturing the polymer matrix capsule surrounding the
drug.
 Initially this process occurs at the outer environment of the
polymeric matrix, but gradually proceeds towards the
interior of the matrix.
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27. Marketed Products
PRODUCT
NAME
ACTIVE DESIGN DOSE
Acutrim Phenylpropanola
mine
Elementary
pump
75 mg
Alpress LP Prazosin Push -Pull 2.5 - 5 mg
Cardura XL Doxazosin Push -Pull 4, 8 mg
Covera HS Verapamil Push -Pull with
time delay
180, 240 mg
Ditropan XL Oxybutinin
chloride
Push -Pull 5, 10 mg
Dynacirc CR Isradipine Push -Pull 5, 10 mg
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References
 Novel drug delivery system , volume 50,
Y.W.Chien
 The theory & practice of industrial pharmacy,
Leon Lachman , Herbert A.Lieberman,
Joseph L.Kanig,3 rd edition.
www.google.com

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